“We tried not to smile, for smiling only encourages men to bore you and waste your time.”

“A smile is the only infectious affliction everyone is encouraged to spread.”

“There are only so many of us born at a time and we are thrown into the world to find each other, to find the other ones who don't think you're strange, who understand your jokes, your smile, the way you talk.There are only so many of us born at a time and we only have so long to find each other before we die.But we have to try.”

“Be generous with your smile and try not to frown.And you will see my children; your smile will never let you down ☺”

“Leela: Why are we listening to them? It is a waste of time.The Doctor; It is difficult to know what will be a waste of time until after the time has been wasted, by which time it is too late. So predicting what will be a waste of time is something of a waste of time. Unless it gives you pleasure of course when it probably doesn't count as a waste of time.Leela (yawning): I am sorry I did not hear what you said, Doctor.The Doctor (smiling): That was a waste of time then.”

“I don’t regret a single second that I spent with you.” I smiled wryly at him. “No time spent with you is wasted.”